Cutting bit useful for impingement of earth strata

ABSTRACT

A cutting bit for impinging earth strata wherein the cutting bit includes a highly wear-resistant elongate cutting bit body, which has an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. The highly wear-resistant elongate cutting bit body has a maximum transverse dimension and a longitudinal axial length. The cutting bit includes a superhard insert, which is affixed to the head portion at the axial forward end of the cutting bit body. The cutting bit has a slimness ratio, which comprises the ratio of the maximum transverse dimension to the longitudinal axial length wherein the cutting bit exhibits a slimness ratio ranging between about 0.15 and about 0.60.

BACKGROUND OF THE INVENTION

The present invention pertains to a cutting bit for impingement of earth strata. More specifically, the present invention pertains to a cutting bit for impingement of earth strata wherein the cutting bit, which exhibits excellent wear resistance and impact resistance, encounters less resistance and exhibits better rotational properties and longer useful tool life than prior cutting bits.

Heretofore, cutting bits (e.g., rotatable cutting bits) used for mining, trenching and construction applications including a road planing applications comprise an elongate steel cutting bit body. Such cutting bits also comprise a hard (e.g., cemented (cobalt) tungsten carbide) insert affixed to the axial forward end of the cutting bit body. The bore of a holder (or block) retains (in a rotatable fashion or in a non-rotatable fashion) the cutting bit at its axial rearward end. During operation such as, for example, in a road planning application, a driven drum carries a plurality of holders, each of which in turn, carries a cutting bit. The drum drives the cutting bit into impingement with the earth strata (e.g., asphaltic material of a highway) thereby breaking or disintegrating the earth strata into pieces. Since the cutting bit, and especially the cutting bit body, experience severe forces, it is very desirable that the cutting bit body possess optimum properties (e.g., wear resistance and impact resistance) suitable to withstand such a severe operating environment for an acceptable duration.

Heretofore, the typical cutting bit body used in a cutting bit for mining and construction applications has an elongate steel body that presents a relatively wide collar wherein the collar is the portion of the cutting bit body that has the greatest transverse dimension. In the case of a cutting bit with a cutting bit body of a generally cylindrical geometry, the collar is the portion that has the greatest diameter. The collar is relatively wide because the cutting bit body must have a sufficient amount of strength (or impact resistance) and wear resistance.

While the cutting bits that have the wide collar function in a satisfactory fashion, there is a drawback with these cutting bits. This drawback is that the wide collar presents a greater volume or mass of material of the cutting bit that must pass through the earth strata. This results in an increase in the resistance the cutting bit encounters upon impingement of the earth strata. Such an increase in resistance results in an increase in energy necessary to break up the earth strata, which increases fuel consumption and overall operating costs, as well as decreases or reduces overall operational efficiency for the specific application. In the case of a road planing bit, the bit impinges roadway materials such as, for example, asphaltic material. Thus, it would be highly desirable to provide an improved cutting bit that does not encounter as much resistance upon impingement of the earth strata as earlier cutting bits. By providing such a cutting bit, the fuel consumption and overall operating costs will decrease and the overall operational efficiency will increase.

As mentioned above, a cutting bit with a wider profile encounters more resistance upon impingement of the earth strata. By encountering more resistance, the cutting bit exhibits a higher rate of wear, which, in turn, causes the cutting bit to become blunter thereby reducing the overall cutting efficiency. An operator must replace more often cutting bits that experience a higher rate of wear as opposed to cutting bits that experience a lower rate of wear. In the case of a road planing application, and there can be a great amount of time spent to change out an entire set of road planing bits on a road planing drum. Thus, it would be highly desirable to provide a cutting bit that exhibits a slimmer profile thereby encountering less resistance upon impingement of the earth strata. Such a cutting bit with a slimmer profile would exhibit a lower rate of wear thereby taking a greater amount of time to become blunter, and hence, increase the overall operational efficiency of the cutting or mining or road planing operation in.

In a coal mining operation, it is most desirable if the coal is broken in to larger pieces or chunks. By doing so, fewer small particulates and fines such as, for example, coal dust, are generated during the coal mining operation. This is a desirable result since there is concern over the excessive generation of small particulates such as coal dust. In the case where the cutting bit presents a wider profile or geometry, there is the tendency for the cutting bit to pulverize the coal upon impingement, which generates small particulates. The use of a cutting bit with a wider profile results in a higher incidence of generating small particulates due to the increased resistance of the cutting bit impinging the substrate (e.g., vein of coal). Therefore, it would be highly desirable to provide an improved cutting bit that upon impingement of the earth strata (or substrate) does not result in the excessive generation of small particulates and fines such as, for example, coal dust. Further, it would be highly desirable to provide such an improved cutting bit that actually reduces the amount of small particulates and fines generated during a coal mining operation.

In the process of a cutting bit impinging the earth strata, it is desirable that the cutting bit exhibit acceptable strength or impact resistance and wear resistance. Impact resistance is desirable because the earth strata can be inconsistent in that it may contain hard anomalies. For example, in a mining operation the earth strata may contain rocks or the like in a formation of softer coal or minerals. In a road planing operation such as planing asphaltic roadway material, the cutting bits may impact a manhole cover or the life during the course of the planing operation. In a trenching operation, the cutting bits may encounter rocks or other very hard regions. Wear resistance is necessary because of the highly abrasive nature of the earth strata (e.g., asphaltic material).

During the process of a rotatable cutting bit impinging the earth strata, it is very beneficial that the rotatable cutting bit freely rotate about its central longitudinal axis. Free rotation about its central longitudinal axis maintains the geometric symmetry of the cutting bit about its central longitudinal axis, which typically results in a longer useful tool life. It would be highly desirable to provide an improved cutting bit that freely rotates about its central longitudinal axis. It would also be highly desirable to provide an improved cutting bit that possesses an inherent capability to rotate freely about its central longitudinal axis.

It is apparent that it would be very desirable to provide an improved cutting bit that encounters less resistance upon impingement of the earth strata, and yet exhibits acceptable strength or impact resistance and wear resistance. It is also apparent that it would be very desirable to provide an improved rotatable cutting bit that is freely rotatable to maintain its geometric symmetry about its central longitudinal axis. It is further apparent that it would be highly desirable to provide an improved cutting bit that exhibit an inherent capability to rotate freely about its longitudinal axis.

SUMMARY OF THE INVENTION

In one form thereof, the invention is a cutting bit for impinging earth strata. The cutting bit comprises a highly wear-resistant elongate cutting bit body that has an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. The highly wear-resistant elongate cutting bit body has a maximum transverse dimension and a longitudinal axial length. The cutting bit has a superhard insert affixed to the head portion at the axial forward end of the cutting bit body. The cutting bit exhibits a slimness ratio comprising the ratio of the maximum transverse dimension to the longitudinal axial length wherein the slimness ratio ranging between about 0.15 and about 0.60.

In another form thereof, the invention is a cutting bit for impinging earth strata. The cutting bit comprises a highly wear-resistant elongate cutting bit body that has an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. At least a part of the highly wear-resistant elongate cutting bit body comprises a hard component-matrix composite material to provide wear resistance. The cutting bit has a hard insert affixed to the head portion at the axial forward end of the cutting bit body.

In yet another form thereof, the invention is a cutting bit for impinging earth strata. The cutting bit comprises a highly wear-resistant elongate cutting bit body that has an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. The highly wear-resistant elongate cutting bit body has a maximum transverse dimension and a longitudinal axial length. The highly wear-resistance cutting bit body comprises a substrate, and at least a part of the substrate has a hardfacing layer thereon. The cutting bit has a hard insert affixed to the head portion at the axial forward end of the cutting bit body. The cutting bit exhibits a slimness ratio that comprises the ratio of the maximum transverse dimension to the longitudinal axial length wherein the slimness ratio ranges between about 0.15 and about 0.25.

In still another form thereof, the invention is a cutting bit for impinging earth strata. The cutting bit comprises a highly wear-resistant elongate cutting bit body that has an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. The highly wear-resistant elongate cutting bit body carries a wear rotator to provide wear resistance. The cutting bit has a hard insert affixed to the head portion at the axial forward end of the cutting bit body.

In another form thereof, the invention is a cutting bit for impinging earth strata. The cutting bit comprises a highly wear-resistant elongate cutting bit body that has an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. The highly wear-resistant elongate cutting bit body has a maximum transverse dimension and a longitudinal axial length. The cutting bit has a hard insert affixed to the head portion at the axial forward end of the cutting bit body. The cutting bit has a slimness ratio comprising the ratio of the maximum transverse dimension to the longitudinal axial length wherein the cutting bit exhibits a slimness ratio ranging between about 0.15 and about 0.25.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings that form a part of this patent application:

FIG. 1 is a side view (with a portion of the cutting bit body broken away) of a first specific embodiment of a rotatable cutting bit of the invention that comprises an elongate cutting bit body, which comprises in its entirety a hard component-matrix material, wherein a hard insert affixes to the cutting bit body and wherein there is shown the ratio of the maximum transverse dimension (E) to the longitudinal axial length (B);

FIG. 2 is a side view (with a portion of the cutting bit body broken away) of a second specific embodiment of a rotatable cutting bit of the invention wherein the cutting bit body comprises a head portion made from a hard component-matrix composite material and a shank portion made from steel and a hard insert, which is a serrated-style of cutting insert, affixes within a socket in the head portion;

FIG. 2A is a cross-sectional view of the axial forward end of the cutting bit body of FIG. 2 showing the generally cylindrical socket that receives the hard insert;

FIG. 2B is a cross-sectional view of the intersection between the axial rearward portion and the axial forward portion of the cutting bit of FIG. 2 showing the saw-tooth geometry of the contact area (or intersection) between these components;

FIG. 3 is a side view (with a portion of the cutting bit body broken away) of a third specific embodiment of a rotatable cutting bit of the invention wherein the cutting bit body comprises an axial forward portion made of a hard component-matrix composite material and an integral head and shank portion made of steel, which carries a long resilient retainer-washer assembly (the washer is shown in a non-operative position by solid lines and in an operative position by broken lines), and wherein a plug-style of hard insert affixes to the axial forward portion;

FIG. 3A is a cross-sectional view of the intersection between the axial rearward portion and the axial forward portion of the cutting bit of FIG. 3 showing the sinusoidal geometry of the contact area (or intersection) between these components;

FIG. 4 is a side view (with a portion of the cutting bit body broken away) of a fourth specific embodiment of a rotatable cutting bit of the invention comprising a cutting bit body, which comprises a steel portion and a hard component-matrix composite portion, that includes an axial forward head portion that contains a plurality of generally cylindrical hard rotator wear members wherein a flat-bottom style of hard insert affixes to the cutting bit body;

FIG. 5 is a side view (with a portion of the cutting bit body broken away) of a fifth specific embodiment of a rotatable cutting bit of the invention comprising a cutting bit body, which comprises a steel body with a hardfacing deposit, that includes an axial forward head portion that contains a plurality of generally triangular hard rotator wear members wherein a hard insert affixes to the cutting bit body;

FIG. 6 is a side view (with a portion of the cutting bit body broken away) of a sixth specific embodiment of a rotatable cutting bit of the invention comprising a cutting bit body, which is made entirely of steel, that includes an axial forward head portion that contains a plurality of generally rectangular hard rotator wear members wherein a valve-seat style of hard insert affixes to the cutting bit body;

FIG. 6A is a cross-sectional view of cutting bit of FIG. 6 taken along the section line 6A-6A in FIG. 6;

FIG. 6B is a portion of the cross-sectional view FIG. 6A illustrated the joint between the steel bit body and one of the rotator wear members wherein the steel bit body has experienced wear during the operation;

FIG. 7 is a side view (with a portion of the coating layer broken away) of a seventh specific embodiment of a rotatable cutting bit body of the invention comprising an elongate cutting bit body made from steel with a coating layer of a hard component-matrix material on the head portion of the cutting bit body and wherein there is shown the ratio of the maximum transverse dimension (I) to the longitudinal axial length (M);

FIG. 8 is a side view (with a portion of the cutting bit body broken away) of an eighth specific embodiment of a rotatable cutting bit of the invention having an elongate cutting bit body made of steel and presenting a mediate wear region and wherein a hard insert affixes within the socket of the cutting bit body;

FIG. 9 is an isometric view of a ninth specific embodiment of a cutting bit of the invention having a cutting bit that carries a mediate wear member and wherein a hard insert affixes within the socket of the cutting bit body;

FIG. 10 is a side view of the specific embodiment of the rotatable cutting bit of FIG. 9 with the cutting bit body shown in cross-section;

FIG. 11 is a side view of a tenth specific embodiment of a cutting bit of the invention with the cutting bit body and mediate wear region shown in cross-section and wherein a polycrystalline diamond (PCD) hard insert affixes within a socket of the cutting bit body;

FIG. 11A is a cross-sectional view of the hard insert from the tenth specific embodiment of FIG. 11 showing the polycrystalline diamond region and the cemented carbide backing region of the hard insert; and

FIG. 12 a side view of another specific embodiment of a highly wear-resistant cutting bit body wherein the slimness ratio is about 0.150.

DETAILED DESCRIPTION

Referring to the drawings, FIG. 1 illustrates a first specific embodiment of a rotatable cutting bit of the invention for impinging the earth strata, wherein the cutting bit is generally designated as 20. Here, earth strata refers to a wide variety of substrate-type materials upon which the cutting bit impinges thereby breaking earth strata into pieces. The specific earth strata can vary depending upon the particular application. For example, in a mining application, earth strata may comprise the mined material such as coal or the like. In a trenching application, earth strata may comprise dirt and in some cases concrete. In a road planing application, earth strata may comprise the roadway materials such as, for example, asphaltic roadway material and concrete roadway material. In addition, there is the contemplation that the rotatable cutting bits of the invention are useful in foundation drilling, rock cutting, and drilling for oil and/or gas deposits. Further, although the specific embodiments illustrated herein comprise a rotatable cutting bit, there is the contemplation that the invention has application and includes non-rotatable cutting bits in that these bits do not rotate about their central longitudinal axis during operation.

The rotatable cutting bit 20, which has an overall axial length equal to dimension A-I, and comprises an elongate cutting bit body 22, which is a highly wear-resistant cutting bit body, that has a central longitudinal axis A-A about which the cutting bit 20 rotates during operation. The cutting bit body 22 has an axial forward end 24 and an opposite axial rearward end 26. There is an enlarged dimension head portion (see bracket 30) at the axial forward end 24 and a reduced dimension shank portion (see bracket 32) at the axial rearward end 26. In this specific embodiment, the highly wear-resistant elongate cutting bit body 22 is made of a hard component-matrix composite material. However, as an alternative, the cutting bit body maybe made of any one of a cemented carbide or a substrate with a coating layer wherein the coating layer being a material selected from the group consisting of hardfacing including hardfacing applied by a plasma transferred arc process, polycrystalline diamond, diamond (e.g., a CVD diamond film), cubic boron nitride, and polycrystalline cubic boron nitride.

One should appreciate that a highly wear-resistant elongate cutting bit body exhibits a wear resistance greater than the wear resistance of a cutting bit body made from steel compositions typically used heretofore to make cutting bit bodies.

Cutting bit body 22 further contains at its axial forward end 24 a valve seat-style socket 34 adapted to receive a hard insert 40 so that the hard insert 40 affixes to the head portion 30 at the axial forward end 24 of the cutting bit body 22. Although the hard insert 40 will be described in more detail hereinafter, the hard insert can be made from material selected from the group including a hard component-matrix composite material, and a substrate with a coating layer wherein the coating layer being a material selected from the group consisting of hardfacing including hardfacing applied by a plasma transferred arc process, polycrystalline diamond (PCD), diamond, cubic boron nitride, and polycrystalline cubic boron nitride (PcBN). The hard insert may also be made from other hard materials known to those in the art to be suitable to function as a hard insert in a cutting bit. There should be an appreciation at the above materials are also suitable for use as the hard insert (or superhard insert) in other specific embodiments disclosed herein. There should also be an appreciation that some of the materials are what those skilled in the art consider to be superhard materials. Superhard materials include polycrystalline diamond, diamond (e.g., a CVD diamond film), cubic boron nitride, and polycrystalline cubic boron nitride. A superhard insert is an insert made from a superhard material.

Shank portion 32 contains an annular groove 36 near the axial rearward end 26 of the cutting bit body 22 wherein the groove 36 is adapted to receive a resilient retainer 38. When the cutting bit 20 is inserted into the bore of a holder or block (not illustrated) typically used to carry a cutting bit, the resilient retainer 38 expands in a radial outward direction to frictionally engage the wall of the bore and thereby rotatably retain the cutting bit within the bore. There should be an understanding that the cutting bit 20 may use other known ways to retain the cutting bit within the bore of the holder.

As disclosed by the broken away portion of the cutting bit body 22 adjacent to the axial forward end 24 thereof, all of the elongate cutting bit body 22 is made of a hard component-matrix composite material. The hard component-matrix composite material is disclosed in U.S. Pat. No. 6,984,454 to Majagi entitled WEAR-RESISTANT MEMBER HAVING A HARD COMPOSITE COMPRISING HARD CONSTITUENTS HELD IN AN INFILTRANT MATRIX, that is assigned to Kennametal Inc., and is hereby incorporated in its entirety by reference herein. Although it will become apparent from the description hereinafter, it is contemplated that as an alternative, only a portion of the cutting bit body rather than the entire cutting bit body could be made of the hard component-matrix composite material. Further, there should be an appreciation that reference to the term hard component-matrix composite material (or a like term) refers to the material disclosed and described in U.S. Pat. No. 6,984,454 to Majagi.

Although more specific compositions are set forth below and in U.S. Pat. No. 6,984,454, the hard component-matrix composite material comprises a plurality of discrete hard constituents and matrix powder of hard particles and an infiltrant alloy bonded together to form the hard component-matrix composite. A more detailed description of the hard constituents, the matrix powder and the infiltrant alloy is set forth hereinafter.

In reference to the geometry of the cutting bit body 22 as illustrated in FIG. 1, the axial length of the entire cutting bit body is equal to the dimension “B”. The axial length of the head portion 30 is equal to dimension “C” and the axial length of the shank portion 32 is equal to dimension “D”. The head portion 30 presents a generally frusto-conical shape wherein the minimum transverse dimension (or diameter) is equal to dimension “F” and the maximum transverse dimension (or diameter) is equal to dimension “E”. The maximum transverse dimension of the head portion 30 exists at the collar 42 of the cutting bit body 22. The transverse dimension of the head portion 30 gradually increases in the axial rearward direction at an angle equal to dimension “H” and a fillet transitions the frusto-conical surface into the collar 42. The transverse dimension (or diameter) of the shank portion 32 is constant and is equal to dimension “G”. Table A below sets forth selected dimensions and ranges of dimensions from the specific embodiment of the cutting bit 20 illustrated in FIG. 1.

TABLE A Selected Dimensions and Ranges of Dimensions for Cutting Bit 20 Preferred Dimension (millimeters Preferred Range for unless Dimension (millimeters Dimension & Description otherwise noted) unless otherwise noted) A-1 - axial length of entire 234 200-260 cutting bit 20 B-1 height of hard insert 15.75 10-20 from axial end of the cutting bit body B - axial length of cutting 218.25 180-240 bit body C - axial length of head 86.25 75-95 portion D - axial length of shank 132 120-145 portion E - maximum transverse 64 50-70 dimension of head portion 30 F - minimum transverse 30 20-40 dimension of head portion 30 G - transverse dimension 35 25-45 of shank portion 32 H - angle of decrease of 5 degrees 2 degrees to 8 degrees transverse dimension of head portion 30 E/B ratio (slimness ratio) 0.29 0.26-0.32 E/A ratio 0.27 0.26-0.28

Based upon the above dimensions, there should be an appreciation that the ratio between the maximum transverse dimension of the head portion to be axial length of the cutting bit body (E/B) can vary within a specified range. More specifically, one preferred range for the ratio E/B is between about 0.26 and about 0.32. A specific value for the ratio E/B is 0.29. However, there should be an appreciation that the E/B slimness ratio could range between about 0.150 to about 0.600. There is the contemplation that the slimness ratio could be between about 0.150 and about 0.250 and between about 0.150 and about 0.200.

One can see that the specific embodiment of the cutting bit as illustrated in FIG. 1 is a cutting bit for impinging earth strata wherein the cutting bit comprises a highly wear-resistant elongate cutting bit body, which has an axial forward end and an axial rearward end. The cutting bit body has an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. Here, there should be an appreciation that essentially all of the highly wear-resistant cutting bit body is made from the hard component-matrix composite material to provide wear-resistance. When the insert is made from a superhard material, there is a superhard insert, which is affixed to the head portion at the axial forward end of the cutting bit body. The superhard insert may be made from a material different than the material of the cutting bit body. The cutting bit has a slimness ratio, which is the ratio of the maximum transverse dimension to the longitudinal axial length. The slimness ratio can range between about 0.150 to about 0.600.

Table B sets forth dimensions along the line of the dimensions in Table A, except that the cutting bits pertain to a construction tool and a trenching tool. The construction tool cutting bit body is a model RZ25 construction tool made and sold by Kennametal Inc. of Latrobe, Pa. 15650. The trenching cutting bit body is a model TS2 trenching tool made and sold by Kennametal Inc. of Latrobe, Pa. 15650.

TABLE B Selected Dimensions and Ranges of Dimensions for a Typical Construction Tool and a Typical Trenching Tool Construction Tool - Trenching Tool - Preferred Dimension Preferred Dimension (millimeters unless (millimeters unless Dimension & Description otherwise noted) otherwise noted) A-1 - axial length of entire 88.6 167 cutting bit B-1 height of hard insert 19 — from axial end of the cutting bit body B - axial length of cutting 69.6 159.6 bit body C - axial length of head 29.9 82 portion D - axial length of shank 39.7 77.6 portion E - maximum transverse 38.1 63.5 dimension of head portion F - minimum transverse 24 15.7 dimension of head portion G - transverse dimension 19.9 26.8 of shank portion H - angle of decrease of — 6 degrees transverse dimension of head portion E/B ratio 0.55 0.40 E/A ratio 0.43 0.38

Referring to FIG. 2, there is illustrated a second specific embodiment of a rotatable cutting bit for impinging earth strata wherein the cutting bit is generally designated as 50. Cutting bit 50 has a cutting bit body generally designated as 52 and which has an axial rearward portion 54 and an axial forward portion 64. In this specific embodiment, the axial rearward portion 54 is made of steel and the axial forward portion 64 is made of the hard component-matrix composite material. One should appreciate that instead of comprising the hard component-matrix composite material, the axial forward portion 64 may comprise a wear-resistant steel material. One should further appreciate that the axial rearward portion 54 and that the axial forward portion 64 may comprise steel of the same composition or of different compositions. Typically, in the case where the axial or portion 64 comprises of steel, such steel would be more wear-resistant than the steel comprising the axial rearward portion 54.

The axial rearward portion 54 has an axial forward end 56 and an axial rearward end 58. The axial rearward portion 54 contains an annular groove 60 adjacent to the axial rearward end 58, as well as a conically-shaped portion 62 adjacent to the axial forward end 56. One should appreciate that the geometry of the axial forward end 56 of the axial rearward portion 54 may be something other than of a conical geometry. For example, the geometry of the axial forward and 46 may be dendritic, planar, or non-planar wherein the objective is to increase the amount of surface area over which the axial rearward portion 54 contacts the axial forward portion 64. Typically, in the case when an infiltration method is utilized to bonded together these two components, the bonding strength increases with an increase in the surface area over which the two components are in contact. A resilient retainer 63 is within the groove 60. Resilient retainer 63 functions in a fashion like that of retainer 38.

The axial forward portion 64 has an axial forward end 66 and an axial rearward end 68. The axial forward portion 64 contains a cylindrical socket 72 at the axial forward end 66 and a conically-shaped socket 70 at the axial rearward end 68. A hard insert 73, which can comprise a superhard material such as, for example, polycrystalline diamond, polycrystalline cubic boron nitride, contains an axial forward conical portion 74 and an axial rearward cylindrical portion, which presents a plurality of radially projecting axial serrations 75. The hard insert 73 affixes within the cylindrical socket by press fitting wherein the tool body surrounding the socket 72 deforms upon entry of the hard insert 73 into the socket 72 to frictionally retain the insert in the socket. However, there should be an appreciation that other methods could affix the hard insert 73 within the socket 72 wherein these other methods can include without limitation brazing, gluing and shrink fitting. Further, even though in this specific embodiment insert 73 projects past the axial forward end 66, there should be an appreciation that the insert 73 may be flush with the surface of the axial forward end 66. In addition, there should be an appreciation that the shape of the hard insert 73 could take on any one of a number of different geometries. For example, rather than the axial forward portion of the hard insert 73 being generally conical, it could present a geometries such as shown by hard insert 134 in FIG. 4.

The conical socket 70 in the axial forward portion 64 receives the conical portion 62 of the axial rearward portion 54 so that the axial forward portion 64 affixes by brazing or the like to the axial rearward portion 54. There should be an appreciation that other methods could affix the axial forward portion 64 to the axial rearward portion 54 wherein these other methods can include without limitation gluing, press fitting, shrink fitting and other mechanical means. In addition, an infiltration process such as disclosed in U.S. Pat. No. 6,984,454 to Majagi is appropriate to use to affix together the axial forward portion 64 to the axial rearward portion 54. In such an arrangement, one could position the steel axial rearward portion 54 in a mold and position the components of the hard component-matrix composite about the conical portion 62 of the axial rearward portion 54 and then infiltrate the same so as to metallurgically join the axial forward portion 64 to the axial rearward portion 54.

Referring to FIG. 2B, the interface generally designated as 71 is between the axial forward portion 64 and the axial rearward portion 54. The interface 71 presents a non-planar surface in the form of a saw-tooth configuration. Such a geometry provides a non-planar surface area at the interface.

One can appreciate that the specific embodiment of the cutting bit as illustrated in FIG. 2 is a cutting bit for impinging earth strata wherein the cutting bit comprises a highly wear-resistant elongate cutting bit body having an axial forward end and an axial rearward end. There is an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. There is a superhard insert affixed to the head portion at the axial forward end of the cutting bit body. The superhard insert being made from a material different than the material of the cutting bit body. The highly wear-resistant elongate cutting bit body includes at the axial forward end thereof an axial forward portion of the cutting bit body made of a material selected from the group consisting of a hard component-matrix composite material, a cemented carbide, and a substrate with a coating layer wherein the coating layer selected from the group consisting of hardfacing including hardfacing applied by a plasma transferred arc process, polycrystalline diamond, and cubic boron nitride.

Referring to FIG. 3, there is illustrated a rotatable cutting bit for impinging earth strata wherein the cutting bit is generally designated as 80. Cutting bit 80 has a cutting bit body generally designated as 82 and which comprises an axial rearward portion 84 and an axial forward portion 100. The axial rearward portion 84 is made from steel and the axial forward portion 100 is made from the hard component-matrix composite material of U.S. Pat. No. 6,984,454 to Majagi.

The axial rearward portion 84 has an axial forward end 86 and an axial rearward end 88. Axial rearward portion 84 has a head portion 94 with an enlarged diameter collar and a reduced diameter shank portion 87. The axial rearward portion 84 contains an annular groove 95 in the shank 87 adjacent to the axial rearward end 88. The axial rearward portion 84 contains a large diameter socket 90 in the axial forward end 86 thereof. A small diameter socket 92 is in the bottom surface of the large diameter socket 90. A resilient long retainer 96 is carried within the groove 95. Retainer 96 functions in a fashion generally like retainer 38 in that it expands in a radial outward direction to frictionally engage the wall of the bore in the holder.

The assembly further includes a washer 98 wherein FIG. 3 illustrates the washer in an inoperative position by solid lines and in an operative position by broken lines. Very briefly, prior to insertion of the shank of the cutting bit into the bore of the holder, the washer surrounds the retainer. Upon the insertion of the shank into the bore, the washer contacts the forward surface of the holder and the washer travels in an axial forward direction along the retainer. Once the shank of the cutting bit is fully within the bore, the washer is sandwiched between the rearward surface of the collar and the forward surface of the holder.

The axial forward portion 100 has an axial forward end 102 and an axial rearward end 104. The axial forward portion 100 contains a cylindrical socket 106 at the axial forward end 102. A generally cylindrical post 108 projects from the axial rearward end 104. A plug-style hard insert 109, which can comprise a superhard material such as, for example, polycrystalline diamond, polycrystalline cubic boron nitride, affixes by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) within the cylindrical socket 106. The sockets 90 and 92 in the axial rearward portion 84 receive the axial forward portion 100 (including the post 108 being received within the socket 92) so that the axial forward portion 100 affixes by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) to the axial rearward portion 84. There should be an appreciation that an infiltration process such as disclosed in U.S. Pat. No. 6,984,454 to Majagi is appropriate to use to affix together these components. In such an arrangement, one can position the steel component (i.e., the axial rearward portion 84) in a mold, and then position the components of the hard component-matrix composite that form the axial forward potion 100 about the steel component and infiltrate the same thereby metallurgically joining the components (i.e., axial rearward portion 84 and axial forward portion 100) together.

FIG. 3A illustrates the joinder between axial forward portion 100 and cutting bit body 82. The area of the joinder between these components is generally designated as 111. As can be seen, the area of joinder 111 presents a non-planar surface in the form of a sinusoidal shape. Such a geometry provides a non-planar surface area at the interface.

Referring to FIG. 7, there is illustrated a seventh specific embodiment of the rotatable cutting bit body generally designated as 200. The cutting bit body 200 has an axial forward end 204 and an axial rearward end 206. Cutting bit body 200 has an axial forward portion (see bracket 208) adjacent the axial forward end 204 and an axial rearward portion (see bracket 210) adjacent the axial rearward end 206. Although not illustrated, the axial forward portion contains socket adapted to receive a hard insert. The axial rearward portion 210 contains an annular groove that receives a resilient retainer 216 in a fashion like that of retainer 38 in FIG. 1. There is a coating 212 on the generally frusto-conical surface 214 of the axial forward portion 208. In this embodiment, the coating is made of the hard component-matrix composite material as disclosed by U.S. Pat. No. 6,984,454 to Majagi; however, it is contemplated that the coating could comprise a material selected from the group consisting of hardfacing, polycrystalline diamond, cubic boron nitride, and PTA. In the case where the exterior region is the hard component-matrix composite material, the infiltration method of U.S. Pat. No. 6,984,454 to Majagi could be used to make the cutting bit body.

In reference to the geometry of the cutting bit body 200, the axial length of the entire cutting bit body is equal to the dimension “I”. The axial length of the axial forward portion 208 is equal to the sum of the dimension “J” and “K” and the axial length of the axial rearward portion 210 is equal to dimension “L”. The axial forward portion 208 presents a generally frusto-conical shape wherein the minimum transverse dimension (or diameter) is equal to dimension “N” and the maximum transverse dimension (or diameter) is equal to dimension “M”. The maximum transverse dimension of the axial forward portion 208 exists at the collar of the cutting bit body. A fillet provides a transition between the frusto-conical surface and the collar. The transverse dimension of the axial forward portion gradually increases in the axial rearward direction at an angle equal to dimension “S”. The transverse dimension (or diameter) of the axial rearward portion 210 is constant and is equal to dimension “O”. Table B below sets forth selected dimensions and ranges of dimensions from the specific embodiment of the cutting bit body 200.

TABLE B Selected Dimensions and Ranges of Dimensions for Cutting Bit Body 200 Preferred Dimension (millimeters Preferred Range for unless Dimension (millimeters Dimension & Description otherwise noted) unless otherwise noted) I - axial length of entire 218.25 210-240 cutting bit body J - axial length of head 73.25 60-85 portion forward of the collar K - axial length of the 13  5-20 collar L - axial length of axial 132 115-145 rearward portion 210 M - maximum transverse 64 50-75 dimension of axial forward portion 208 N - minimum transverse 30 20-40 dimension of axial forward portion 208 O - transverse dimension 35 25-45 of axial rearward portion 210 S - angle at which 5 degrees 2 degrees to 8 degrees transverse dimension of axial forward portion gradually increases in the axial rearward direction

Based upon the above dimensions, there should be an appreciation that the ratio between the maximum transverse dimension of the head portion to be axial length of the cutting bit body (M/I) can vary within a specified range. More specifically, the specific ratio M/I is 0.325. One preferred range of M/I is between about 0.250 and about 0.450. There is the contemplation that the M/I ratio can range between as low as about 0.150 to as high as about 0.600. There is the expectation that an especially preferred range of M/I is between about 0.150 and about 0.250 with an even more preferred range between about 0.150 and about 0.200.

In reference to the specific embodiment illustrated by FIGS. 1, 2, 3 and 7, the hard component-matrix composite material exhibits impact resistance and wear resistance properties that are better than steels commonly used to make the cutting bit bodies. Thus, by using the hard component-matrix composite material (or other hard materials disclosed above), overall geometry of the cutting bit body of the cutting bit is slimmer than the geometry of earlier cutting bits. By providing a geometry or profile that is slimmer, the cutting bit encounters less resistance when impinging the earth strata. The cutting bit thus overcomes drawbacks of earlier cutting bits that have a wide collar. By decreasing the amount of resistance the cutting bit encounters upon impingement of the earth strata, there is a decrease in the energy necessary to break up the earth strata, which decreases fuel consumption and decreases overall operating costs. By providing a geometry or profile that is slimmer, there is an overall increase in operational efficiency.

Referring to FIG. 4, there is illustrated a fourth specific embodiment of a rotatable cutting bit generally designated as 110. Cutting bit 110 has a cutting bit body 112 with an axial forward end 114 and an axial rearward end 116. The cutting bit body 112 has an axial rearward portion 129 made of steel joined at the intersection or interface 127 to in axial forward portion 125 made of a hard component-matrix composite material. The interface 127 presents a saw-tooth geometry. Cutting bit 110 has a central longitudinal axis P-P. Cutting bit body 112 has an enlarged dimension head portion (see bracket 118) and a reduced dimension shank portion (see bracket 120). The reduced to dimension shank portion 120 is integral with the axial rearward portion of the head portion 118. The axial forward portion 125 contains a flat bottom style socket 124 at the axial forward end 114 of the cutting bit body 112. The socket 124 is adapted to receive a hard insert wherein hard insert 134, which can comprise a superhard material such as, for example, polycrystalline diamond, polycrystalline cubic boron nitride, affixes by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) within the socket 124. Methods like brazing and gluing use an attachment material such as, for example, a braze alloy or glue, to attach the wear rotator to the cutting bit body. Methods like press-fitting in shrink-fitting do not use an attachment material to attach the wear rotator to the cutting bit body. The means to attach the wear rotators in the embodiment of FIG. 4 are applicable to the embodiments of FIGS. 5 and 6. There should be an appreciation that, as an alternative, the axial rearward cylindrical portion of hard insert 134 could present serrations like such as, for example, serrations 75 in the hard insert 73 of cutting bit 50 as illustrated in FIG. 2.

The shank portion 120 contains a groove 130 that receives a resilient retainer 132. Retainer 132 functions like the retainer 38 of the first specific embodiment of the cutting bit 20.

Head portion 118 contains a plurality of recesses 126 that are generally cylindrical in shape. Recesses 126 exhibit a somewhat random orientation; however, recesses 126 may exhibit a specific intentional pattern to provide specific wear properties or characteristics. A cylindrical discrete rotator wear member 128 affixes by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) into each one of the recesses 126. In this embodiment, a portion of the surface of each one of the discrete rotator wear members 128 extends past the surface of the head portion 118 so as to present an exposed rotator (or side or lateral) surface. There should be an appreciation and that the discrete rotator wear members 128 may also be flush with the surface of the head portion 118 or, as an alternative, be recessed within the recesses 126 relative to the surface of the head portion 118.

The discrete wear rotator members may be made of a hard material such as, for example, cemented (cobalt) tungsten carbide or the hard component-matrix composite material or cubic boron nitride, polycrystalline diamond material or polycrystalline cubic boron nitride. Further, there should be an appreciation that the discrete wear rotator members can comprise a volume or mass of hard coating (e.g., PCD) either on the surface or in the recesses or a weld bead either on the surface or in the recesses of the head portion 118. The rotator wear members facilitate the rotation of the cutting bit about its central longitudinal axis and a description of this feature is set forth hereinafter.

Still referring to FIG. 4, there is an appreciation that rotatable cutting bit 110 presents a cutting bit body that includes a portion of the hard component-matrix composite material and a portion of steel, a rotatable cutting bit further includes rotator wear members that are fixed to the cutting bit body.

Referring to FIG. 5, there is illustrated a rotatable cutting bit generally designated as 140. Cutting bit 140 has a cutting bit body 142 with an axial forward end 144 and an axial rearward end 146, and a central longitudinal axis Q-Q. Cutting bit body 142 is made of steel. Cutting bit body 142 has an enlarged dimension head portion (see bracket 148) and a reduced dimension shank portion (see bracket 150). The head portion 148 contains a socket 154 at the axial forward end 144 of the cutting bit body 142. The socket 154 is adapted to receive a hard insert wherein hard insert 164, which can comprise a superhard material such as, for example, polycrystalline diamond, polycrystalline cubic boron nitride, affixes by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) within the socket 154. The head portion 148 has a hardfacing deposit 157 thereon adjacent the axial forward end 144 thereof. The hardfacing can be applied by any conventional means including the plasma transferred arc method. The shank portion 150 contains a groove 160 that receives a resilient retainer 162. Retainer 162 functions like the retainer 38 of the first specific embodiment of the cutting bit 20.

Head portion 148 contains a plurality of recesses 156 that are generally triangular in shape. Recesses 156 exhibit an orientation comprising two rows about the circumference of the head portion 148. However, as mentioned above, the recesses do not have to present a specific orientation in that the recesses can be randomly contained in the cutting bit or have an orientation that is asymmetric about the central longitudinal axis. There is the contemplation that the recesses may be in a helical or spiral orientation. A discrete rotator wear member 158 affixes by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) into each one of the recesses 156. In this embodiment, a portion of the surface of the discrete rotator wear member 158 extends past the surface of the head portion 148 so as to present an exposed surface. Further, there should be an appreciation that the discrete wear rotator members can comprise a volume or mass of hard coating (e.g., PCD) either on the surface or in the recesses or a weld bead either on the surface or in the recesses of the head portion. The rotator wear members facilitate the rotation of the cutting bit about its central longitudinal axis and a description of this feature is set forth hereinafter. There is the expectation of an enhancement to the rotation of the cutting bit when the rotator wear members are in a helical or spiral arrangement.

Still referring to FIG. 5, there is an appreciation that rotatable cutting bit 110 presents a cutting bit body that includes a portion of the hard component-matrix composite material and a portion of steel, a rotatable cutting bit further includes rotator wear members that are fixed to the cutting bit body.

Referring to FIG. 6, there is illustrated a rotatable cutting bit generally designated as 170. Cutting bit 170 has a cutting bit body 172 with an axial forward end 174 and an axial rearward end 176. Cutting bit body 172 has an enlarged dimension head portion (see bracket 178) and a reduced dimension shank portion (see bracket 180). The head portion 178 contains a valve seat-style socket 184 at the axial forward end 174 of the cutting bit body 172. The valve seat-style socket 184 is adapted to receive a hard insert wherein hard insert 194, which can comprise a superhard material such as, for example, polycrystalline diamond, polycrystalline cubic boron nitride, affixes by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) within the socket 184. The shank portion 180 contains a groove 190 that receives a resilient retainer 192. Retainer 192 functions like the retainer 38 of the first specific embodiment of the cutting bit 20.

Head portion 178 contains a plurality of recesses 186 that are generally rectangular in shape. Recesses 186 are oriented in a row about the circumference of the head portion 178. A discrete rotator wear member 188 affixes by brazing or the like into each one of the recesses 186. In this embodiment, a portion of the surface of the discrete rotator wear member 188 extends past the surface of the head portion 178 so as to present an exposed surface. Further, there should be an appreciation that the discrete wear rotator members can comprise a volume or mass of hard coating (e.g., PCD) either on the surface or in the recesses or a weld bead either on the surface or in the recesses of the head portion. The rotator wear members facilitate the rotation of the cutting bit about its central longitudinal axis and a description of this feature is set forth hereinafter.

In reference to the rotator wear members contained in the specific embodiments of FIGS. 4, 5 and 6, there should be an appreciation that the rotator wear members can take on most any one of a number of different geometries. The fact that the cutting bits of FIGS. 4, 5 and 6 present wear members that exhibit specific geometries should not limit the scope of the invention to any specific geometry of rotator wear member. There should be an appreciation that the rotator wear members may be of most any size, shape, or orientation, as well as project in a radial outward direction the same or differing distances from the surface of the cutting bit or be embedded in the cutting bit body the same or differing depths. There should be an appreciation that the perimeter weighting can be symmetrical about the central longitudinal axis of the cutting bit or can be asymmetrical about the central longitudinal axis of the cutting bit.

Referring to FIG. 6A, a left side rotator wear member 188C (as viewed in FIG. 6A) extends a radial distance “T” from the surface of the cutting bit body. A right side rotator wear member 188A (as viewed in FIG. 6A) extends a radial distance “U” from the surface of the cutting bit body. A comparison of these wear members 188A and 188C demonstrates that the wear members can extend or project in a radial outward direction differing distances from the surface of the cutting bit. Still referring to FIG. 6A, the top wear member 188B is embedded in the cutting bit body a depth “V” while the bottom wear member 188 is embedded into the cutting bit body a depth “W”. A comparison of these wear members 188 and 188B shows that the wear members can be embedded varying depths in the cutting bit body.

Referring to the specific embodiments illustrated in FIGS. 4, 5 and 6, the discrete rotator wear members facilitate the rotation of the cutting bit about its longitudinal axis during its operation via two fundamental ways. The first way has to do with the centrifugal force generated to the heavier perimeter weighting of the head portion of the cutting bit. The second has to do with the impingement of the debris upon the side or lateral surfaces of the discrete rotator wear members.

In reference to the centrifugal force generated to the heavier perimeter weighting of the head portion of the cutting bit, the discrete rotator wear members are at the periphery or perimeter of the head portion of the cutting bit. This is illustrated in FIG. 6A, which is a cross-sectional view of the cutting bit of FIG. 6 taken along section line 6A-6A. The orientation of the rotator wear members as shown in FIG. 6A is representative of the other embodiments (i.e., cutting bits of FIGS. 4 and 5) that have peripheral rotator wear members. In a typical case, the material for the rotator wear members is heavier (i.e., a greater density) than the material for the head portion. Thus, a plurality of the rotator wear members at the periphery of the head portion creates a heavier perimeter weighting of the head portion. Once the cutting bit has begun to rotate during operation, the heavier perimeter weighting of the head portion of the cutting bit create centrifugal forces and an inertia that facilitate the rotation of the cutting bit.

In reference to the impingement of the debris upon the side or lateral surfaces of the discrete rotator wear members, during operation, the cutting bit impinges the earth strata to break the earth strata into pieces. These pieces 200 impinge against the exposed surfaces (e.g., the side surfaces or lateral surfaces of the rotator wear members) 189 of the discrete rotator wear members 188 to facilitate the rotation of the cutting bit about its central longitudinal axis. FIG. 6A shows this feature wherein debris 200 impinges against the exposed side surface 189 of the rotator wear member 188. The force of the impinging material functions to help push or urge the cutting bit to rotate about its central longitudinal axis.

As the operation continues the head portion experiences abrasive wear to increase the amount of exposed surface of the discrete rotator wear members. This is shown in FIG. 6B. FIG. 6B illustrates that the joint between the bit body and the bottom rotator wear member after the bit body has experienced wear during operation. As is apparent from a comparison of FIGS. 6A and 6B, the amount of exposed side surface increases the effect of the debris 200 or pieces of earth strata impinging upon the exposed surface 189 increases (i.e., exerts a greater force from the impingement of debris 200 due to an increase in surface area) to better facilitate the rotation of the cutting bit.

It can thus be seen that each one of the cutting bits of FIGS. 4, 5 and 6 provides a rotatable cutting bit with the capability to enhance the continual rotation thereof during use. The perimeter weighting (e.g., via the rotator wear members) provides an inertia that enhances the rotation of the cutting bit. The presence of the exposed surfaces of the wear members also enhances the rotation of the cutting bit during use. The discrete rotator members, which provide perimeter weighting and rotator surface area, result in beneficial features to the cutting bit. There should be an appreciation that the presence of grooves, and especially helical grooves, in the axial forward head portion of the cutting bit can enhance the continual rotation of the cutting bit during use. In this regard, the debris impinges against the surfaces that define the grooves. This impingement essentially helps drive or push the cutting bit to rotate.

Referring to FIG. 8, there is illustrated an eighth specific embodiment of the rotatable cutting bit of the invention for impinging earth strata wherein the cutting bit is generally designated as 220. Cutting bit 220 has a cutting bit body 222 with an axial forward end 224 and an axial rearward end 225. Cutting bit body 222 has an axial forward portion (see bracket 226) and an axial rearward portion (see bracket 228). The axial forward portion 226 has a reduced diameter section 234 wherein the reduced diameter section 234 defines an interior surface 236 generally parallel to the central longitudinal axis T-T and a pair of opposite surfaces (i.e., a forward transverse surface 238 and a rearward transverse surface 240) generally perpendicular to the central longitudinal axis T-T.

The cutting bit 220 further includes a mediate wear region generally designated as 244. In this embodiment, the mediate wear region 244 includes an inner split ring 246 that has an interior surface 248 and an exterior surface 250, as well as a forward surface 251. The mediate wear region 244 further includes an outer split ring 252 that has an interior surface 254 and an exterior surface 256, as well as a rearward surface 258. These rings typically comprise two pieces.

When assembled to the cutting bit body, the inner ring 246 is closest to the reduced diameter section 234 so that the interior surface 248 contacts and affixes to the interior surface 236 of the reduced diameter section 234 and the forward surface 251 contacts and affixes to the forward transverse surface 238. The interior surface 254 of the outer ring 252 contacts and affixes to the exterior surface 250 of the inner ring 246, and the rearward surface 258 contacts and affixes to the rearward transverse surface 240. These rings (246, 248) affix to one another and the cutting bit body by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means).

In this specific embodiment, the inner ring 246 is made of the hard component-matrix composite material and the outer ring 252 is made of steel. The inventors contemplate that the outer ring could be made of the hard component-matrix composite material and the inner ring could be made of steel. The inventors further contemplate that the inner and outer rings could be made of the hard component-matrix composite material of different compositions. There is the contemplation that a plasma transferred arc process can be useful to deposit hard material to form the inner ring 246. The plasma transferred arc process is used to use a metallic coating to a substrate in order to prove its resistance against where and/or corrosion. During the process, metal powder is fed into a molten weld puddle generated by a plasma arc at a high temperature (e.g., 20,000° C.). An exemplary plasma transferred arc system is available through PLASMA Team Snc (see internet website: http://www.plasmateam.com).

There should be an appreciation that an infiltration process such as disclosed in U.S. Pat. No. 6,984,454 to Majagi is appropriate to use to affix together these rings. In such an arrangement, one can position the one of the rings in a mold, and then position the components of the hard component-matrix composite about the steel component and infiltrate the same thereby metallurgically joining the components together. Further, there should be an appreciation that the entire mediate wear region could be made of the hard component-matrix composite material using the infiltration techniques.

The axial rearward portion 228 contains a groove 230 that receives a resilient retainer 232. Retainer 232 functions like the retainer 38 of the first specific embodiment of the cutting bit 20.

Referring to FIGS. 9 and 10, there is illustrated a rotatable cutting bit for impinging earth strata wherein the cutting bit is generally designated as 350. Cutting bit 350 has a cutting bit body 352. Cutting bit 350 has an axial forward portion 354, a mediate wear region 356, and axial rearward portion 358. The axial forward portion 354 has an axial forward end 360 and an axial rearward end 362. The axial forward portion 354 contains a socket 364 adapted to receive a hard insert wherein the hard insert 380 affixes to the axial forward portion 354 by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means). The mediate wear region 356 has an axial forward end 366 and an axial rearward end 368. The mediate wear region 356 contains a forward socket 370 at the axial forward end 366 thereof and a rear socket 372 at the axial rearward end 368 thereof. The axial rearward portion 358 has an axial forward end 376 and an axial rearward end 378.

The socket 370 in the mediate wear region 356 receives the axial forward portion 354 and the socket 372 in the mediate wear region 356 receives the axial rearward portion 358. The axial forward portion 354 and the axial rearward portion 358 each affix by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means) to the mediate wear region 356. Hot isostatic pressing (HIP) or rapid omnidirectional compaction (ROC) techniques can make the mediate wear region 356. The mediate wear region 356 can comprise a hard material such as, for example, the hard component-matrix composite material and any one of the following materials: a matrix material (e.g., nickel steel) were in the hard components include cast carbides, spherical cast carbide, and macrocrystalline carbides. There is also the expectation that the hard components may comprise polycrystalline diamond.

Referring to FIG. 11, there is illustrated a rotatable cutting bit for impinging earth strata wherein the cutting bit is generally designated as 290. Cutting bit 290 has a cutting bit body 292. Cutting bit 290 has an axial forward portion 294, a mediate wear region 302, and axial rearward portion 314. The axial forward portion 294 has an axial forward end 295 and an axial rearward end that includes a projection 298. The axial forward portion 294 contains a socket 296 adapted to receive a polycrystalline diamond (PCD) insert 297 wherein the hard insert 297 affixes to the axial forward portion 294 by brazing or the like (or in the alternative can be affixed by methods that include without limitation gluing, press fitting, shrink fitting and other mechanical means). There is the contemplation that the hard insert 297 may comprise cemented cobalt tungsten carbide. The mediate wear region 302 has an axial forward end 304 and a axial rearward end 306. The mediate wear region 302 contains a forward socket 308 at the axial forward end 304 thereof and a rear socket 310 at the axial rearward end 306 thereof. The axial rearward portion 314 has an axial forward end 316 and an axial rearward end 318.

The forward socket 308 in the mediate wear region 302 receives the axial forward portion and the rearward socket 310 in the mediate wear region receives the axial rearward portion. The axial forward portion and the axial rearward portion each affix by brazing or the like to the mediate wear region. There should be an appreciation that an infiltration process such as disclosed in U.S. Pat. No. 6,984,454 to Majagi is appropriate to use to affix together these components. In such an arrangement, one can position the steel component in a mold, and then position the components of the hard component-matrix composite about the steel component and infiltrate the same thereby metallurgically joining the components together.

In reference to the PCD insert 297, it has an axial forward PCD region 330 of polycrystalline diamond material and a backing region 332 that provide support for the PCD region. The axial forward PCD region 330 presents a conical geometry. U.S. Pat. No. 6,344,149 to Oles, which is hereby incorporated by reference herein, discloses techniques to make the PCD insert. While most all of the axial forward PCD portion may comprise polycrystalline diamond, there should be an appreciation that the axial forward PCD region may comprise a conical backing with a layer of PCD thereon.

Referring to FIG. 12, there is illustrated another specific embodiment of a rotatable cutting bit generally designated as 500. Rotatable cutting bit 500 includes a highly wear-resistant cutting bit body generally designated as 502, which has an axial forward end 504 and an axial rearward end 506. The highly wear-resistant cutting bit body 502 has an axial length of dimension “AA”. In this specific embodiment, highly wear-resistant cutting bit body 502 is made of the hard component-matrix composite material. However, there should be an appreciation that the highly wear-resistant cutting bit body 502 may comprises a hard material such as, for example, a cemented carbide. As another option, the highly wear-resistant cutting bit body 502 may comprise a substrate with a superhard coating layer, or in the alternative, the highly wear-resistant cutting bit body 502 may carry one or more wear rotators.

The highly wear-resistant cutting bit body 502 has an enlarged head portion 508 adjacent the axial forward end 504 thereof and a reduced shank portion 510 adjacent to the axial rearward end 506 thereof. A collar 512 separates the head portion 508 from the shank portion 510. The collar 512 has a maximum transverse dimension “BB”. The rotatable cutting bit 500 has a retainer 514 at the axial rearward end 506 of the highly wear-resistant cutting bit body 502. The rotatable cutting bit 500 has a superhard insert 516 at the axial forward end 504 of the highly wear-resistant cutting bit body 502. The superhard insert 516 extends a distance “CC” past the axial forward end 504 of the highly wear-resistant cutting bit body 502. The slimness ratio of BB/AA, i.e., the ratio of the maximum transverse dimension to the axial length, is about 0.150.

There should be an appreciation that the cutting bit of the present invention provides an increase in useful tool life for a number of reasons. The use of a superhard material for the hard insert at the axial forward end of the cutting bit enhances the penetration of the cutting bit into the earth strata or substrate. This feature by itself increases the useful tool life of the cutting bit. The use of a cutting bit body that exhibits enhanced wear resistance lengthens the time the cutting bit body to maintain its structural integrity. Like for a hard insert comprising a superhard material, this feature by itself increases the useful tool life of the cutting bit.

The combination of the use of a superhard material for the hard insert in combination with a cutting bit body that exhibits enhanced wear resistance provides for an exceptional increase in the useful tool life of the cutting bit. More specifically, heretofore, the use of a superhard hard insert in connection with a conventional cutting bit body possesses the imitation that the useful life of the cutting bit body terminates prior to the termination of the useful life of the superhard insert. The typical consequences of the superhard insert, which still possesses useful tool life, becomes detached from the cutting bit body upon the cutting bit body wearing past its useful life. However, in the case of the combination of a superhard insert and a cutting bit body with enhanced wear resistance, the cutting bit body maintains its structural integrity thereby providing support to the superhard insert for a longer time. Thus, the termination of the useful life of the cutting bit body with enhanced wear resistance more closely matches the termination of the useful tool life of the superhard insert. The appropriation of the beneficial properties of the superhard insert and the cutting bit body with enhanced wear resistance results in a cutting bit exhibits enhanced useful tool life.

Some of the components of the cutting bits are made of steel. In reference to steel alloy compositions, the steel alloys listed in Table 1 are suitable for the manufacture of steel alloy components of cutting bits. While Table 1 lists suitable steel alloys, there should be appreciation that steel alloys other than those set forth in Table 1 below may be suitable for use in the manufacture of the cutting bit.

TABLE 1 Steel Alloys (Weight Percent) Suitable for Manufacture of Components of Cutting Bits Alloy C % Mn % Ni % Cr % Mo % S % P % Si % Other % Fe 15B37 0.30-0.39 1.00-1.50 — — — 0.03 0.03 .15-.35 B = .0005-.003 Balance max max P/F 0.20-0.80 0.10-0.25 1.75-2.00 0.10 0.50-0.60 0.03 0.03 0.03 Cu = 0.15 Balance 46XX max max max max max 4140 0.38-0.43 0.75-1.00 — 0.8-1.1 0.15-0.25 0.03 0.03 0.15-0.35 — Balance max max ASTM 0.48-0.53 — — 0.80-1.00 — 0.03 0.03 0.15-0.35 V = 0.15 Balance A231 max max minimum A232

In reference to the composition of the cemented tungsten carbide useful for the hard inserts at the axial forward end of the cutting bit, the cemented tungsten carbides may be any one of a number grades of cemented tungsten carbide that are suitable for impingement of earth strata. These cemented tungsten carbide grades may include grades that comprise between about 0.01 weight percent and about 35 weight percent cobalt with the balance tungsten carbide (the average grain size varies between about 0.01 microns and about 25 microns) and recognized impurities, as well as in the alternative various additives (e.g., the carbides, nitrides and/or carbonitrides of the elements (except for tungsten) of Group IVa, Va, and VIa of the Periodic Table). Typical grades of cemented (cobalt) tungsten carbide have a hardness of less than or equal to about 88.5 Rockwell A. An exemplary grade of cemented tungsten carbide comprises the following about 6 weight percent cobalt with the balance tungsten carbide (average grain size ranging between about 4 microns to 10 microns) and recognized impurities, and has a hardness equal to about 89.5 Rockwell A. Other grades of cobalt-bonded cemented carbides (and their properties) are disclosed in the article by Santhanam et al., entitled “Cemented Carbides” Metals Handbook Volume 2, 10^(th) Edition Properties and Selection, wherein this article is hereby incorporated in its entirety by reference herein.

In reference to the hard component-matrix composite material, it comprises a plurality of discrete hard constituents (described hereinafter) wherein these hard constituents are held within a matrix. The matrix comprises a mass of matrix powder that comprises different kinds of hard particles and/or powders, and an infiltrant alloy that has been infiltrated into the mass of the matrix powder and the hard constituents under the influence of heat and sometimes under additional environmental influences such as, for example, in a pressure or in a vacuum. Furthermore, the infiltrant alloy may be infiltrated into the mass of hard constituents and matrix powder under various atmospheres (e.g., argon, helium, hydrogen, and nitrogen).

The hard constituents may comprise sintered cemented carbide members (which hereinafter may be called sintered cemented carbide members) that can be of various geometric shapes such as, for example, triangular. As one option, the hard constituent can present a specific pre-determined shape depending upon the specific application. As an alternative, a hard sintered cemented carbide member could be crushed to obtain hard constituents wherein the hard constituents are crushed particles of a larger size wherein the particle size is measured by mesh size (e.g., −80+120 mesh).

As one option, the hard constituents can be selectively positioned within the matrix of the hard composite which typically occurs in the mold prior to infiltration. It is contemplated that the hard constituents may cover between about 0.5 percent to about 90 percent of the surface area of the wear-resistant hard member. There is no intention to restrict the invention to the specific positioning of the hard constituents in the hard composite. For example, the hard constituents may be uniformly (or non-uniformly or randomly) distributed throughout the volume of the hard composite.

By mentioning the above specific hard constituent, there is no intention to limit the scope of the invention to this specific hard constituent. It is contemplated that other materials would be suitable for use as the hard constituents in the hard composite. In this regard, the following materials would appear to be suitable for use as hard constituents in the hard composite: sintered cemented tungsten carbide wherein a binder includes one or more of cobalt, nickel, iron and molybdenum; coated sintered cemented tungsten carbide wherein a binder includes one or more of cobalt, nickel, iron and molybdenum, and the coating comprises one or more of nickel, cobalt, iron and molybdenum; one or more of the carbides, nitrides, and borides of one or more of titanium, niobium, tantalum, hafnium, and zirconium; one or more of the coated carbides, coated nitrides, and coated borides of one or more of titanium, niobium, tantalum, hafnium, and zirconium wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; chromium carbides; coated chromium carbides; coated silicon carbide wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; and coated silicon nitride wherein the coating comprises one or more of nickel, cobalt, iron, copper, molybdenum or any other suitable metal; and coated boron carbide wherein the coating comprises one or more of nickel, cobalt, iron, copper, molybdenum, and any other suitable metal.

The matrix powder can comprise a crushed cemented carbide particle. The crushed cemented carbide particles may be present in a size range for these crushed cemented carbide particles equal to −325+200 mesh. Another size range for these crushed cemented carbide particles is −80+325 mesh. The standard to determine the particle size is by using sieve size analysis and the Fisher sub-sieve size analyzer for −325 mesh particles. One composition for the crushed cemented carbide particles is cobalt cemented tungsten carbide wherein the cobalt ranges between about 6 weight percent and about 30 weight percent of the cobalt cemented tungsten carbide material and tungsten carbide is the balance of the material. Another preferred composition for crushed cemented carbide particles is cobalt cemented tungsten carbide wherein the cobalt ranges between about 0.2 weight percent and about 6 weight percent of the cobalt cemented tungsten carbide material and tungsten carbide is the balance of the material.

By mentioning specific compositions, there is no intention to limit the scope of the invention to these specific cemented carbides. It is contemplated that other cemented carbides (e.g., chromium carbide) would be suitable for use as the crushed cemented tungsten carbide particles in the hard composite. In this regard, the carbides could be different from tungsten carbide (e.g., titanium carbide and chromium carbide) and the binder could be different from cobalt (e.g., nickel). It is further contemplated that the crushed cemented carbide particles may vary in composition throughout a particular hard composite depending upon the specific application. It is also contemplated that certain hard materials other than cemented carbides may be suitable to form these particles.

The matrix powder may also contain crushed cast carbide particles wherein one size range for these particles is −325 mesh. Another size range for these particles is −80 mesh. One composition for these particles is cast tungsten carbide. It is contemplated that the crushed cast carbide particles may vary in composition throughout a particular hard composite depending upon the specific application. It is further contemplated that other cast carbides or hard materials are suitable for use in place or along with the crushed cast carbide particles.

The matrix powder may further include in addition to crushed cemented carbide particles and/or crushed cast carbide particles, any one or more of the following: crushed carbide particles (e.g., crushed tungsten carbide particles that have a size of −80+325 mesh), steel particles that have an exemplary size of −325 mesh, carbonyl iron particles that have an exemplary size of −325 mesh, cemented carbide powder, and coated (e.g., nickel coating) cemented carbide particles, and nickel-coated tungsten carbide particles (−80+325 mesh).

It is desirable that the infiltrant alloy has a melting point that is low enough so as to not degrade the hard constituents upon contact therewith during the infiltration process. Along this line, the infiltrant alloy has a melting point that ranges between about 500 degrees Centigrade and about 1400 degrees Centigrade. It is contemplated that the infiltrant alloys may have a melting point that ranges between about 600 degrees Centigrade and about 800 degrees Centigrade. It is further contemplated that the infiltrant alloys may have a melting point that ranges between about 690 degrees Centigrade and about 770 degrees Centigrade. It is still further contemplated that the infiltrant alloys may have a melting point below about 700 degrees Centigrade. Exemplary general types of infiltrant alloys include copper-based alloys such as, for example, copper-silver alloys, copper-zinc alloys, copper-nickel alloys, copper-tin alloys, and nickel-based alloys including nickel-copper-manganese alloys. Exemplary infiltrant alloys are set forth in Table 2 herein below.

TABLE 2 Compositions of Infiltrant Alloys in Weight Percent Solidus Alloy/ (Melting Liquidus (Flow Composition Cu Ni Zn Mn Ag Sn Nb Point) (° C.) Point) ° C. A-1 53 15  8 24 — — — 1150 202 45 — 35 — 20 — — 710 815 255 40 — 33 — 25 2 — 690 780 559 42  2 — — 56 — — 770 895 700 20 — 10 — 70 — — 690 740 Cu—20Ni—10Mn 70 20 — 10 — — — ~1100 Macrofil 56 56 — 43 — — 1 — 866 888 Macrofil 65 65 15 20 — — — — 1040 1075 Macrofil 49 49 10 41 — — — — 921 935 C96800 81.8 10 — — — 8 0.2 1050 1150 Cu—20Ni—20Mn 60 20 — 20 — — — 1030 1050 Cu—25Ni—25Mn 50 25 — 25 — — — 1030 1050 By mentioning specific infiltrant alloys in Table 2, there is no intention to limit the scope of the invention to infiltrant alloys with these specific compositions and/or properties. As one alternative, the composition of the infiltrant alloy could be within the range of 5-40 weight percent nickel, 5-40 weight percent manganese and the balance copper.

Referring to an exemplary hard component-matrix composite material, the hard particles in the hard composite may comprise 100 percent crushed nickel cemented chromium carbide particles. The nickel could comprise between about 3 weight percent and about 25 weight percent of the cemented carbide with chromium carbide comprising the balance. The preferred composition of the cemented carbide is about 15 weight percent nickel and the balance chromium carbide. The particle size of the crushed cemented (nickel) chromium carbide particles can range between about −325 mesh and about +80 mesh. The infiltrant alloy can comprise between about 60 weight percent and about 80 weight percent of the hard composite and the crushed nickel cemented chromium carbides can comprise between about 20 weight percent and about 40 weight percent of the hard composite.

Referring to another exemplary hard component-matrix composite material, it can also be made from the compositions set forth in Table 3 below. The matrix powder is Mixture No. 2 taken from Table 4 hereof. The hard constituents are crushed nickel cemented chromium carbide wherein the nickel is present in an amount of 15 weight percent. The particle size of the crushed cemented (nickel) chromium carbide particles can range between about −325 mesh and about +80 mesh. The titanium diboride (TiB₂) particles have a particle size equal to −325 mesh. The infiltrant alloy was the copper-based alloy A-I set forth in Table 1. The infiltrant alloy comprised between about 60 weight percent and about 70 weight percent of the hard composite.

TABLE 3 Compositions of the Hard Composite Crushed Nickel Titanium Matrix Powder Cemented Diboride Mixture No. 2 from Chromium Carbide Particles (−325 Table 2 hereof (−325 + 80 mesh) mesh) (weight Composition (weight percent) (weight percent) percent) 1-A 40 40 20 2-A 80 20 3-A 66 34 4-A 66 34 5-A 50 50

In yet another example of the hard constituent-matrix composite, there are a plurality of sintered cemented carbide members that typically have a composition of 10 weight percent cobalt and the balance tungsten carbide. The matrix powder typically includes tungsten carbide, chromium carbide, as well as cobalt and nickel in the form of a binder alloy for the carbides and/or a coating on the carbides. One typical infiltrant alloy has a composition (weight percent) of copper(53%)-nickel(15%)-manganese(24%)-zinc(8%) and a melting point equal to about 1150 degrees Centigrade.

Another exemplary composition for the hard constituent-matrix composite material comprises hard constituents that comprise one or more sintered carbides wherein these carbides include tungsten, titanium, niobium, tantalum, hafnium, chromium and zirconium. The matrix powder typically comprises one or more sintered carbides, crushed sintered carbides, cast carbide, crushed carbides, tungsten carbide powders and chromium carbide powders. The infiltrant alloy has a composition (weight percent) of copper(53%)-nickel(15%)-manganese(24%)-zinc(8%) and a melting point equal to about 1150 degrees Centigrade.

In still another exemplary composition, the hard constituents that comprise crushed cemented tungsten carbide having a particle size equal to −80+120 mesh. The cemented carbide is cobalt cemented tungsten carbide where the cobalt is present in an amount of 10 weight percent. The hard composite further contains a matrix powder that could be any one of the matrix powders set forth in Table 2 through Table 6 hereof, but preferred a matrix powder may be any one of Matrix Powders Nos. 1 through 3 set forth in Table 4 hereof. The ratio by weight of the matrix powder to the infiltrant alloy is about 40:60 by weight. In some applications, the hard constituent crushed cemented tungsten carbide particles (−80+120 mesh) range between about 2.5 volume percent and about 40 volume percent of the hard composite with the balance comprising matrix powder and infiltrant alloy. However, there are some applications in which the crushed cemented tungsten carbide particles range between about 2 volume percent to about 4 volume percent of the hard composite. There are also other applications in which the crushed cemented tungsten carbide particles range between about 30 volume percent and about 40 volume percent of the hard composite.

In yet another exemplary embodiment, the hard constituents may comprise one or more sintered carbides wherein these carbides include tungsten, titanium, niobium, tantalum, hafnium, chromium and zirconium. The matrix powder typically comprises one or more sintered carbides, crushed sintered carbides, cast carbide, crushed carbides, tungsten carbide powders and chromium carbide powders. The infiltrant alloy has a composition of copper(53%)-nickel(5%)-manganese(24%)-zinc(8%) and a melting point equal to about 1150 degrees Centigrade.

The hard constituent-matrix composite material can comprise crushed cemented tungsten carbide having a particle size equal to −80+120 mesh. The cemented carbide is cobalt cemented tungsten carbide where the cobalt is present in an amount of 10 weight percent. The hard composite further contains a matrix powder that could be any one of the matrix powders set forth in Table 4 through Table 8 hereof, but preferred a matrix powder may be any one of Matrix Powders Nos. 1 through 3 set forth in Table 4 hereof. The ratio by weight of the matrix powder to the infiltrant alloy is about 40:60 by weight. In some applications, the hard constituent crushed cemented tungsten carbide particles (−80+120 mesh) range between about 2.5 volume percent and about 40 volume percent of the hard composite with the balance comprising matrix powder and infiltrant alloy. However, there are some applications in which the crushed cemented tungsten carbide particles range between about 2 volume percent to about 4 volume percent of the hard composite. There are also other applications in which the crushed cemented tungsten carbide particles range between about 30 volume percent and about 40 volume percent of the hard composite.

In some embodiments, the hard constituents can also comprise cemented carbides, silicon carbides, boron carbide, aluminum oxide, zirconia and other suitable hard materials. The matrix powder typically comprises one or more of crushed tungsten carbide, crushed cemented tungsten carbide, crushed cast tungsten carbide, iron powder, tungsten carbide powder (the tungsten carbide made by a thermit process or from co-carburized tungsten carbide), chromium carbide powder, spherical cast carbide powder and/or spherical sintered carbide powders. The infiltrant alloy has a composition of copper(53%)-nickel(15%)-manganese(24%)-zinc(8%) and a melting point equal to about 1150 degrees Centigrade.

Examples of specific matrix powders (Mixtures Nos. 1 through 20) are set forth in Tables 4 through 8 hereinafter. In reference to the composition of the matrix powders, it should be appreciated that the crushed tungsten carbide component or the crushed cast tungsten carbide component may be substituted, in whole or in part, by spherical sintered tungsten carbide and/or spherical cast tungsten carbide particles. In some cases the spherical sintered tungsten carbide and/or spherical cast carbide particles (or powders) could be used 100% in combination or alone as the hard constituents in the matrix powders.

TABLE 4 Components of the Matrix Powder Mixtures Nos. 1 through 4 (Weight Percent) Constituent (particle size) Mixture No. 1 Mixture No. 2 Mixture No. 3 Mixture No. 4 Crushed tungsten 67 wt. %  67 wt. %  0 wt. % 0 wt. % carbide (−80 + 325 mesh) Crushed tungsten 0 wt. % 15.5 wt. %   0 wt. % 0 wt. % carbide (−325 mesh) Crushed cast 31 wt. %  15.5 wt. %   0 wt. % 0 wt. % tungsten carbide (−325 mesh) 4600 steel (−325 1 wt. % 0 wt. % 0 wt. % 0 wt. % mesh) Carbonyl iron (−325 1 wt. % 0 wt. % 0 wt. % 0 wt. % mesh) Nickel (−325 0 wt. % 2 wt. % 0 wt. % 0 wt. % mesh) Crushed cobalt 0 wt. % 0 wt. % 100 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Crushed nickel 0 wt. % 0 wt. % 100 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh)

TABLE 5 Components of the Matrix Powder Mixtures Nos. 5 through 8 (Weight Percent) Constituent (particle size) Mixture No. 5 Mixture No. 6 Mixture No. 7 Mixture No. 8 Crushed tungsten 63.65 wt. %    63.65 wt. %    0 wt. % 0 wt. % carbide (−80 + 325 mesh) Crushed tungsten 0 wt. % 14.725 wt. %    0 wt. % 0 wt. % carbide (−325 mesh) Crushed cast 29.45 wt. %    14.725 wt. %    0 wt. % 0 wt. % tungsten carbide (−325 mesh) 4600 steel (−325 .95 wt. %   0 wt. % 0 wt. % 0 wt. % mesh) Carbonyl iron (−325 .95 wt. %   0 wt. % 0 wt. % 0 wt. % mesh) Nickel (−325 0 wt. % 1.9 wt. %   0 wt. % 0 wt. % mesh) Crushed cobalt 0 wt. % 0 wt. % 95 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Crushed nickel 0 wt. % 0 wt. % 95 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Chromium 5 wt. % 5 wt. % 5 wt. % 5 wt. % carbide (−45 mesh)

TABLE 6 Components of the Matrix Powder Mixtures Nos. 9 through 12 (Weight Percent) Constituent (particle size) Mixture No. 9 Mixture No. 10 Mixture No. 11 Mixture No. 12 Crushed tungsten 53.6 wt. %   53.6 wt. %   0 wt. % 0 wt. % carbide (−80 + 325 mesh) Crushed tungsten 0 wt. % 12.4 wt. %   0 wt. % 0 wt. % carbide (−325 mesh) Crushed cast 24.8 wt. %   12.4 wt. %   0 wt. % 0 wt. % tungsten carbide (−325 mesh) 4600 steel (−325 .8 wt. %  0 wt. % 0 wt. % 0 wt. % mesh) Carbonyl iron (−325 .8 wt. %  0 wt. % 0 wt. % 0 wt. % mesh) Nickel (−325 0 wt. % 1.6 wt. %   0 wt. % 0 wt. % mesh) Crushed cobalt 0 wt. % 0 wt. % 80 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Crushed nickel 0 wt. % 0 wt. % 0 wt. % 80 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Nickel Coated 20 wt. %  20 wt. %  20 wt. %  20 wt. %  Tungsten Carbide Powder (−325 mesh)

TABLE 7 Components of Matrix Powder Mixtures 13 through 16 (Weight Percent) Constituent (particle size) Mixture No. 13 Mixture No. 14 Mixture No. 15 Mixture No. 16 Crushed tungsten 60.3 wt. %   60.3 wt. %   0 wt. % 0 wt. % carbide (−80 + 325 mesh) Crushed tungsten 0 wt. % 13.95 wt. %    0 wt. % 0 wt. % carbide (−325 mesh) Crushed cast 27.9 wt. %   13.95 wt. %    0 wt. % 0 wt. % tungsten carbide (−325 mesh) 4600 steel (−325 .9 wt. %  0 wt. % 0 wt. % 0 wt. % mesh) Carbonyl iron (−325 .9 wt. %  0 wt. % 0 wt. % 0 wt. % mesh) Nickel (−325 0 wt. % 1.8 wt. %   0 wt. % 0 wt. % mesh) Crushed cobalt 0 wt. % 0 wt. % 90 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Crushed nickel 0 wt. % 0 wt. % 0 wt. % 90 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Crushed nickel 10 wt. %  10 wt. %  10 wt. %  10 wt. %  (15 wt %) cemented chromium carbide(Ni—Cr₃C₂) (−140 + 325 mesh)

TABLE 8 Components of Matrix Powder Mixtures 17 through 20 (in Weight Percent) Constituent (particle size) Mixture No. 17 Mixture No. 18 Mixture No. 19 Mixture No. 20 Crushed tungsten 56.95 wt. %    56.95 wt. %    0 wt. % 0 wt. % carbide (−80 + 325 mesh) Crushed tungsten 0 wt. % 13.175 wt. %    0 wt. % 0 wt. % carbide (−325 mesh) Crushed cast 26.35 wt. %    13.175 wt. %    0 wt. % 0 wt. % tungsten carbide (−325 mesh) 4600 steel (−325 .85 wt. %   0 wt. % 0 wt. % 0 wt. % mesh) Carbonyl iron (−325 .85 wt. %   0 wt. % 0 wt. % 0 wt. % mesh) Nickel (−325 0 wt. % 1.7 wt. %   0 wt. % 0 wt. % mesh) Crushed cobalt 0 wt. % 0 wt. % 85 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Crushed nickel 0 wt. % 0 wt. % 85 wt. %  (10 wt. Percent) cemented tungsten carbide (−140 + 325 mesh) Nickel-coated 15 wt. %  15 wt. %  15 wt. %  15 wt. %  tungsten carbide (−325 mesh)

Additional examples of the hard constituent-matrix composite material are set forth hereinafter. One such example of the hard constituent-matrix composite material comprises sintered cobalt (10 weight percent cobalt) cemented tungsten carbide members and the matrix powder comprised Mixture No. 1 in Table 4 and the infiltrant alloy comprised (in weight percent) a Cu(53%)-Ni(15%)-Zn(8%)-Mn(24%) alloy described above. The matrix powder comprised 40 weight percent and the infiltrant alloy comprised 60 weight percent of the combination of the matrix powder and the infiltrant alloy. Depending upon the specific application, the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 95 weight percent with the balance of the hard composite comprising the matrix powder and the infiltrant alloy. In the alternative and depending upon the specific application, the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 90 percent of the surface area of the hard composite.

For yet another example of the hard constituent-matrix composite material, it comprised a sintered cobalt (6 weight percent cobalt) cemented tungsten carbide member. The matrix powder comprised Mixture No. 4. The infiltrant alloy comprised in weight percent) a Cu(53%)-Ni(15%)-Zn(8%)-Mn(24%). The matrix powder comprised 45 weight percent and the infiltrant alloy comprised 55 weight percent of the combination of the matrix powder and the infiltrant alloy. Depending upon the specific application, the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 95 weight percent with the balance of the hard composite comprising the matrix powder and the infiltrant alloy. In the alternative and depending upon the specific application, the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 90 percent of the surface area of the hard composite.

Still another example of the hard constituent-matrix composite material is a composition that comprises sintered cobalt (6 weight percent cobalt) cemented tungsten carbide cylindrical members. The matrix powder was Mixture No. 3 as set forth in Table 1. The infiltrant alloy comprised (in weight percent) a Cu(53%)-Ni(15%)-Zn(8%)-Mn(24%). The matrix powder comprised 40 weight percent and the infiltrant alloy comprised 60 weight percent of the combination of the matrix powder and the infiltrant alloy. Depending upon the specific application the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 95 weight percent with the balance of the hard composite comprising the matrix powder and the infiltrant alloy. In the alternative and depending upon the specific application, the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 90 percent of the surface area of the hard composite. For some applications, the cemented tungsten carbides may be present in a range between about 1 percent to about 5 percent of the surface area. For other applications, the cemented tungsten carbide members may be present in a range between about 70 percent and about 90 percent of the surface area.

Another example of the hard constituent-matrix composite material comprises nickel-coated sintered cobalt (10 weight percent cobalt) cemented tungsten carbide members. The matrix powder comprised Mixture No. 4 from Table 1. The infiltrant alloy comprised (in weight percent) a Cu(53%)-Ni(15%)-Zn(8%)-Mn(24%). The matrix powder comprised 45 weight percent and the infiltrant alloy comprised 55 weight percent of the combination of the matrix powder and the infiltrant alloy. Depending upon the specific application, the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 95 weight percent with the balance of the hard composite comprising the matrix powder and the infiltrant alloy. In the alternative and depending upon the specific application, the cemented tungsten carbide members were present in a specified amount between about 1 weight percent and about 90 percent of the surface area of the hard composite. For some applications, the cemented tungsten carbide members may be present in a range between about 1 percent to about 5 percent of the surface area. For other applications, the cemented tungsten carbide members may be present in a range between about 70 percent and about 90 percent of the surface area.

It is apparent from the above description that applicants have invented an improved cutting bit In the process of a cutting bit impinging the earth strata, it is desirable that the cutting bit exhibit acceptable strength or impact resistance and wear resistance. Impact resistance is desirable because the earth strata can be inconsistent in that it may contain hard anomalies. For example, in a mining operation the earth strata may contain rocks or the like in a formation of softer coal. In a trenching operation, the cutting bits may encounter rocks or other very hard regions. In a road planing operation such as planing asphaltic roadway material or concrete roadway material, the cutting bits may impact a manhole cover or the life during the course of the planing operation. Wear resistance is necessary because of the highly abrasive mature of the earth strata (e.g., asphaltic material).

It is apparent that the present invention provides an improved cutting bit that freely rotates about its central longitudinal axis. It is also apparent that the present invention provides an improved cutting bit that possesses an inherent capability to rotate freely about its central longitudinal axis.

It is further apparent that the present invention provides a cutting bit that exhibits a slimmer profile thereby encountering less resistance upon impingement of the earth strata. Such a cutting bit with a slimmer profile would exhibit a lower rate of wear thereby taking a greater amount of time to become blunter, and hence, increase the overall operational efficiency of the cutting or mining operation in. Such a cutting bit with a slimmer profile can be achieved by the use of a superhard insert in combination with a highly wear-resistant elongate cutting bit body. There should be an appreciation that the superhard insert is used in the cutting bit typically exhibits longer useful life than a conventional cemented (cobalt) tungsten carbide hard insert. This is especially the case when the superhard insert is used in conjunction with the highly where-resistant elongate cutting pick body. Such a cutting bit with a slimmer profile can also be achieved by the use of a highly wear-resistant elongate cutting bit body in conjunction with a hard insert.

It is also apparent that the present invention provides an improved cutting bit that upon impingement of the earth strata (or substrate) does not result in the excessive generation of small particulates and fines such as, for example, coal dust. There is an advantage connected a cutting bit that actually reduces the amount of small particulates and fines generated during a coal mining operation.

It is apparent that it would be very desirable to provide an improved cutting bit that encounters less resistance upon impingement of the earth strata, and yet exhibits acceptable strength or impact resistance and wear resistance. It is also apparent that it would be very desirable to provide an improved rotatable cutting bit that is freely rotatable to maintain its geometric symmetry about its central longitudinal axis.

The patents and other documents identified herein are hereby incorporated by reference herein. Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or a practice of the invention disclosed herein. There is the intention that the specification and examples are illustrative only and are not intended to be limiting on the scope of the invention. The following claims indicate the true scope and spirit of the invention. 

1. A cutting bit for impinging earth strata, the cutting bit comprising: a highly wear-resistant elongate cutting bit body having an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end, and the highly wear-resistant elongate cutting bit body having a maximum transverse dimension and a longitudinal axial length; a superhard insert affixed to the head portion at the axial forward end of the cutting bit body; and a slimness ratio comprising the ratio of the maximum transverse dimension to the longitudinal axial length, and the slimness ratio ranging between about 0.15 and about 0.60.
 2. The cutting bit according to claim 1 wherein at least a part of the highly wear-resistant cutting bit body comprising a hard component-matrix composite material to provide wear resistance, and the hard component matrix composite material consisting of a plurality of discrete hard constituents and matrix powder of hard particles and an infiltrant alloy bonded together to form the hard component-matrix composite; and the infiltrant alloy having a melting point between about 500 degrees Centigrade and about 1400 degrees Centigrade; the matrix powder comprises one or more of the following: cast carbides, spherical sintered carbides, crushed cemented carbide particles, crushed cast carbide particles, crushed carbide particles, and cemented carbide powder, steel particles, carbonyl iron particles, and coated carbide particles; the discrete hard constituents comprise one or more of cemented carbides and ceramics; sintered cemented tungsten carbide wherein a binder includes one or more of cobalt, nickel, iron and molybdenum; coated sintered cemented tungsten carbide wherein a binder includes one or more of cobalt, nickel, iron and molybdenum, and the coating comprises one or more of nickel, cobalt, iron and molybdenum; one or more of the carbides, nitrides, and borides of one or more of titanium, niobium, tantalum, hafnium, and zirconium; tungsten carbide; one or more of the coated carbides, coated nitrides, and coated borides of one or more of titanium, niobium, tantalum, hafnium, and zirconium wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; coated tungsten carbide wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; coated silicon carbide wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; coated silicon nitride wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; and coated boron carbide.
 3. The cutting bit according to claim 1 wherein at least a part of the highly wear-resistant cutting bit body comprising a wear rotator to provide wear resistance and enhance rotation, and wherein the wear rotator being carried by the highly wear-resistance cutting bit body.
 4. The cutting bit according to claim 3 wherein the wear rotator being attached to the cutting bit body using an attachment material.
 5. The cutting bit according to claim 3 wherein the wear rotator being attached to the cutting bit body without an attachment material.
 6. The cutting bit according to claim 1 wherein the highly wear-resistance cutting bit body comprising a substrate, and at least a part of the substrate having a coating layer thereon, and wherein the coating layer being a material selected from the group consisting of hardfacing including hardfacing applied by a plasma transferred arc process, polycrystalline diamond, diamond, cubic boron nitride, and polycrystalline cubic boron nitride.
 7. The cutting bit according to claim 1 wherein the slimness ratio ranging between about 0.15 and about 0.25.
 8. The cutting bit according to claim 1 wherein the slimness ratio ranging between about 0.15 and about 0.19.
 9. The cutting bit according to claim 1 wherein the superhard insert being selected from the group consisting of a polycrystalline diamond insert, a polycrystalline cubic boron nitride insert, a cubic boron nitride insert, and a superhard coating material-coated insert.
 10. The cutting bit according to claim 9 wherein the superhard coating includes hardfacing including hardfacing applied by a plasma transferred arc process.
 11. A cutting bit for impinging earth strata, the cutting bit comprising: a highly wear-resistant elongate cutting bit body having an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end, and at least a part of the highly wear-resistant elongate cutting bit body comprising a hard component-matrix composite material to provide wear resistance, and a hard insert affixed to the head portion at the axial forward end of the cutting bit body.
 12. The cutting bit according to claim 11 wherein the highly wear-resistant elongate cutting bit body having a maximum transverse dimension and a longitudinal axial length a slimness ratio comprising the ratio of the maximum transverse dimension to the longitudinal axial length, and the slimness ratio ranging between about 0.15 and about 0.60.
 13. The cutting bit according to claim 12 wherein the slimness ratio ranging between about 0.15 and about 0.25.
 14. The cutting bit according to claim 11 wherein the hard component matrix composite material consisting of a plurality of discrete hard constituents and matrix powder of hard particles and an infiltrant alloy bonded together to form the hard component-matrix composite; and the infiltrant alloy having a melting point between about 500 degrees Centigrade and about 1400 degrees Centigrade; the matrix powder comprises one or more of the following: cast carbides, spherical sintered carbides, crushed cemented carbide particles, crushed cast carbide particles, crushed carbide particles, and cemented carbide powder, steel particles, carbonyl iron particles, and coated carbide particles; the discrete hard constituents comprise one or more of cemented carbides and ceramics; sintered cemented tungsten carbide wherein a binder includes one or more of cobalt, nickel, iron and molybdenum; coated sintered cemented tungsten carbide wherein a binder includes one or more of cobalt, nickel, iron and molybdenum, and the coating comprises one or more of nickel, cobalt, iron and molybdenum; one or more of the carbides, nitrides, and borides of one or more of titanium, niobium, tantalum, hafnium, and zirconium; tungsten carbide; one or more of the coated carbides, coated nitrides, and coated borides of one or more of titanium, niobium, tantalum, hafnium, and zirconium wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; coated tungsten carbide wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; coated silicon carbide wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; coated silicon nitride wherein the coating comprises one or more of nickel, cobalt, iron and molybdenum; and coated boron carbide.
 15. The cutting bit according to claim 11 wherein the highly wear-resistant elongate cutting bit body having an axial forward portion adjacent the axial forward end thereof, and the highly wear-resistant elongate cutting bit body having an axial rearward portion adjacent the axial rearward end thereof, and the axial forward portion being attached to the axial rearward portion at an interface, and the interface presenting a non-planar surface area.
 16. A cutting bit for impinging earth strata, the cutting bit comprising: a highly wear-resistant elongate cutting bit body having an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end, and the highly wear-resistant elongate cutting bit body having a maximum transverse dimension and a longitudinal axial length; the highly wear-resistance cutting bit body comprising a substrate, and at least a part of the substrate having a hardfacing layer thereon; a hard insert affixed to the head portion at the axial forward end of the cutting bit body; and a slimness ratio comprising the ratio of the maximum transverse dimension to the longitudinal axial length, and the slimness ratio ranging between about 0.15 and about 0.25.
 17. A cutting bit for impinging earth strata, the cutting bit comprising: a highly wear-resistant elongate cutting bit body having an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end, and the highly wear-resistant elongate cutting bit body carrying a wear rotator to enhance rotation; and a hard insert affixed to the head portion at the axial forward end of the cutting bit body.
 18. The cutting bit according to claim 17 wherein the highly wear-resistant elongate cutting bit body comprising a substrate made of steel, and the steel substrate carrying the wear rotator.
 19. The cutting bit according to claim 17 wherein the wear rotator being attached to the cutting bit body using an attachment material.
 20. The cutting bit according to claim 17 wherein the wear rotator being attached to the cutting bit body without an attachment material.
 21. The cutting bit according to claim 17 wherein the highly wear-resistant elongate cutting bit body being perimeter-weighted, and a plurality of the discrete rotator wear members at the periphery of the head portion.
 22. The cutting bit according to claim 17 wherein the discrete rotator wear members being made of a material selected from the group consisting of a hard component-matrix composite material, a cemented carbide, and a superhard material.
 23. The cutting bit according to claim 17 wherein the discrete rotator wear member presenting an exposed rotator surface against which the pieces of the earth strata impinge during the engagement of the cutting bit with the earth strata, and the exposed rotator surface increases with the duration of the engagement of the cutting bit with the earth strata.
 24. The cutting bit according to claim 17 wherein the head portion having an interior region with a first density and a perimeter region with a second density, and the second density being different from the first density.
 25. The cutting bit according to claim 17 wherein the highly wear-resistant cutting bit body carrying a plurality of the rotator wear members, and the rotator wear members project the same distance from the head portion.
 26. The cutting bit according to claim 17 wherein the highly wear-resistant cutting bit body carrying a plurality of the rotator wear members, and the rotator wear members project differing distances from the head portion.
 27. A cutting bit for impinging earth strata, the cutting bit comprising: a highly wear-resistant elongate cutting bit body having an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end, and the highly wear-resistant elongate cutting bit body having a maximum transverse dimension and a longitudinal axial length; a hard insert affixed to the head portion at the axial forward end of the cutting bit body; and a slimness ratio comprising the ratio of the maximum transverse dimension to the longitudinal axial length, and the slimness ratio ranging between about 0.15 and about 0.25.
 28. The cutting bit according to claim 27 wherein the slimness ratio ranging between about 0.15 and about 0.20. 